Building on the impressive success of the NIH-sponsored workshop "Hydrocephalus: Myths, New Facts and Clear Directions" held in 2005, we propose a subsequent conference "Improving Outcome in Hydrocephalus: Bridging the Gap between Basic Science and Clinical Management" scheduled for September 14-15, 2009 in Baltimore, MD. The conference will be held on September 14-15, 2009 in Baltimore, MD, two days before the annual meeting of the International Society for Hydrocephalus and Cerebrospinal Fluid Research (ISHCSF), which will attract more speakers and attendees and defray expenses for the proposed meeting. The proposed conference will bring together scientists from multiple disciplines including basic neuroscience, neurosurgery, neurology, psychiatry/psychology, neurotrauma, developmental disorders, neural tube defects, bioengineering, infectious disease, diagnostic imaging, and applied mathematics. These experts, many of which are currently involved in hydrocephalus research, as well as others whose studies could bring new innovative approaches into the field, will share novel and recent findings, discuss critical issues, identify emerging scientific opportunities, and provide a focus for translational research that is most likely to produce quantum advancements in the treatment of hydrocephalus. The major goal of the conference will be to understand the critical pathophysiology of hydrocephalus in order to advance clinical applications. The Specific Aims of the meeting are to: (1) Critically re-examine longstanding assumptions about the physiologic and pathophysiologic mechanisms of CSF circulation and intracranial pressure (ICP) and pulsatility, with an emphasis on the impact of these mechanisms on brain function in treated and untreated hydrocephalus;and (2) Identify animal research models, as well as complementary human clinical research paradigms that will advance future study of the aforementioned CSF circulation and ICP mechanisms in parallel so as to identify novel diagnostic and treatment approaches for hydrocephalus. The conference will focus on the following 3 areas in which basic and clinical science have shown great promise since the previous NIH-sponsored workshop: 1. The Influence of Cerebrospinal Fluid Circulation (production, flow and absorption) on Brain Function in Hydrocephalus. This topic, perhaps more than any other, has seen challenges to existing dogmas with new evidence about CSF physiology, including lymphatic, arachnoid, and vascular pathways, choroid plexus physiology, clearance mechanisms, and biomarkers. The conference presentations will address the influence of these new findings on brain function. 2. Intracranial Pressure and Pulsatility. While hydrodynamics and intracranial pressure (ICP) have been studied for many years, new theories and exciting new methodologies, including mathematical modeling and confocal imaging of cerebral capillaries in vivo, are beginning to shed new light on possible pathogenetic mechanisms and endogenous protective responses, vascular permeability, and the predictive value of pulse pressure. The speakers in this session will summarize recent progress and demonstrate potential clinical applications of these mechanisms. 3. Clinically Relevant Animal Models. Advances in our understanding of CSF circulation and ICP mechanisms have prompted new challenges for the in vivo modeling of hydrocephalus. Thus, novel animal models have been produced that include transgenic, congenital and acquired models in developing, mature and aging brains. These models are poised to provide new data on neuron-glial interactions, pharmacological supplements to surgical treatments, and alterations in cerebrovascular pathophysiology that are critical to understanding the pathophysiology of hydrocephalus. Each of these half-day sessions will include plenary presentations by international experts followed by extensive discussion from the audience. A fourth breakout session critiquing and summarizing the key issues of the conference and proposing guidelines and infrastructure to advance hydrocephalus research will conclude the conference. The proceedings of the conference will be published in a well-respected scientific journal and disseminated via appropriate websites. This format and these specific aims will foster the broader goals of the 2005 NIH Hydrocephalus Workshop, including: (1) raising awareness about hydrocephalus research, (2) challenging existing dogmas, (3) identifying the state-of-the-art for important segments of this field, (4) fostering new collaborations in translational research, (5) recruiting new and established investigators to hydrocephalus research, (6) identifying future challenges and opportunities in hydrocephalus research, and (7) disseminating recent progress regarding the pathophysiology and clinical management of hydrocephalus. We expect that this conference will create a substantial increase in the quality and quantity of hydrocephalus research similar to the advances gained from the previous workshop.